An Infra-Red Investigation of the Effect of Pressure on Silica Powders, as Revealed by Deuterium Oxide Exchange

Adsorption of water and 18O exchange of surface hydroxyl groups on silica

“…The same result was obtained for a sample which had not been preheated to 800 "C prior to exchange, although in this case a weak shoulder remains at lower frequency which is due to hydrogen bonded silanols (3,5,7). On other silica samples which had also been preheated to 800 "C, no exchange takes place under similar adsorption conditions at room temperatures, only about 20 "/, exchange occurs at 200 "C and above 500 "C, less than 50 % exchange of silanol groups takes place.…”

“…1A was obtained after Cab-0-Sil had been heated at 800 "C under vacuum for 5 h and shows the well-known band at 3749 cm-' due to non-hydrogen bonded surface silanol (SiOH) groups (3)(4)(5)(6)(7). The spectrum in Fig.…”

“…Canadian Journal of Chemistry, 48, 2454Chemistry, 48, (1970 Infrared spectroscopic techniques have been silica exchange with "0-labeled water under used extensively to investigate the nature of the moderate reaction conditions and that such an silica surface (1)(2)(3)(4)(5)(6)(7). In this communication we exchange can aid in the assignment of infared present some experimental results which demon-absorption bands due to surface-adsorbate strate that the silanol groups on the surface of stretching modes.…”

Investigation of 1800–1400 cm–1region of infra-red spectrum of aerosil silicas

“…A detailed report of this work has been published elsewhere. 10 The results obtained illustrate clearly that when self-supporting pressed discs are made from powders a significant fraction of the available groups on the powder surface are converted to situations within the disc in which they are no longer available for interaction with absorbing molecules. In view of this effect the pressed-disc specimens used for the work described in this and the following paper were prepared in the manner described below unless otherwise stated.…”

Soil Components

“…Separation of the samp1e from the surface is facilitated by introducing a1uminum foil between the samp1e and the stee1 faces. Results obtained on pressed film s may not, however, be exactly comparable to those on free powders, as it has been shown that some surface hydroxyl groups, which can exchange their hydrogen for deuterium in the free powder, are not accessible in the pressed films (HAMBLETON et al [1965]). These se1f-supporting films are adequately transparent in the 3 iLm region, especially when the particle size is of the order of 0.1 iLm ANGELL and SCHAFER [1965]), and have permitted studies of surface hydration and dehydoxylation, which would not otherwise be possible.…”